Cobalt is one of the major metal components which are widely used in various alloys and catalysts. Cobalt is widely distributed in a level of 0.001 to 0.002% in nature, however, it generally exists as an oxide form. Though, most of cobalt metals used in catalysts, alloys and so on, have been collected to prevent environmental pollution, however, they also exits in a form of oxide.
Therefore, many studies have focused on the preparation of highly pure cobalt metals. For example, U.S. Pat. No. 4,093,450 and U.S. Pat. No. 4,452,633 disclose the processes for preparing cobalt metals by reducing cobalt oxides at a high temperature ranging 500 to 775.degree. C. However, the said processes consume high expenses for equipment and operation, since they essentially accompany a reaction step carried out at the high temperature. In addition, Massoth teaches that the cobalt oxides can be reduced in an impregnated form in alumina carrier by hydrogen, however, the efficiency is so low that it cannot be practised in industrial application(s: F. E. Massoth, J. Catal., 15:179(1973)).
Under the circumstances, there are strong reasons for developing an alternative means of preparing cobalt metals at a low temperature with a high degree of purity.